Method for manufacturing composite metal articles



Feb. 27, 1940. R H PKWS 2,191,474

METHOD FOR MANUFACTURING COMPOSITE METAL ARTICLES Filed Dec. 30, 1937 INVENTOR ROBERT K. HOPKINS ATTO R N EY Patented Feb. 27, 1940 1 UNITED STATES METHOD FOR MANUFACTURING 00M- POSITE DIETAL ARTICLES Robert 1:. Hopkins, New York, N. 1., alsiznor to M. W. Kellogg 00., New York, N. Y., a corporation oi Delaware Application December :0, 193-1, sonar No. 1az,4s1

dC'lzims.

This invention relates in general to composite metal-articles and in particular to the manufacture oi composite metal articles made up of a' metal base of one composition coated with a thickness of metal 0! a. diilferent composition having properties and characteristics superior to those of the metal oi the base in the intended service.

This application is a continuation in part o! my applications Serial Nos. 64, 96, 9 d 73, filed respectively on February 18, 1938, February 18, 1936, and August 28, 1937.

The present invention contemplates a. novel method for obtaining unitary composite articles.

In accordance with the method of the present invention a composite article, which may he the final article or the workpiece from which the final article is manufactured, is produced by inti mately uniting, throughout the zone cl union, the coating metal to the base metal.

In one mode oi procedure the metal that is form the coating is placed n container, with a surface 2 hose metal cast o surface. curiae 2e metal posed to the met to fusion or approximately at the level the rising cast metal by on electric current discharge to promote an intermingling cast L l and oatlng metal into a welded unto The esotrlo discharge homered hee forth the surface of the coating metal raised with the rising level oi the cast metal so that the whole of the surface ultimately expoaed to the cast metal is fused with the rising cast metal, alternatively e. plurality of closely spaced discharges may be used so that it will only be necessary to raise them. During this operation the electric discharge may he maintained at or slightly above the level oi the cast metal. To assure a proper weld between the coating metal and the cast lease metal and to protect both :irom the atmosphere, a blanket of protective flux is maintained over the cast metal as well as over the electric energy discharge. The temperature of the cast metal is preferably so chosen that substantial quantities oi the coating metal are not melted by contact therewith so that the depth of the coating metal fused during operation may be more easily controlled.

Alternatively the base metal may be put in i the mold in the solidified condition and the coating metal supplied in the molten condition. i

The further objects and advantages or the invention will be better appreciated from a cop.-

sideratlon oi. the following description of modes of carrying the invention out in practice taken with the accompanying drawing, in which Fig. l is a schematic View, partly in section; illustrating'a manner of carrying out the novel 5) method of the invention;

Figs. '2, 3 and 4 are views, similar tothat or 1', illustrating other modes of carrying out novel method 01 the invention;

Figs. ll, 6, 7 and 8 are crossocational views of the articles produced in accordance with the invention.

The novel method oi this invention may be employed in the manufacture of coated articles of a wide range of compositions. The base metal loe carbon steel, iron, or any oi the metals alloys commonly used in the manufacture of machines, apparatus, vessels, containers, struct al members, etc. The coating metal may be ferrous or non-Jerrous metal or alloy such chrome steel, manganese steel, chrome-nickel moi lei metal etc, having corrosion or oxidar, or other resisting property superior le chosen loose in the intended Llie articles produced icy my novel ,noil, being unit-cry structtu'es, are admirably d to Withstand the severest service condions. i'or instance, those encountered the roleum processing arts where corrosive alums are handl ii at ten' retures in excess lhliil ii. and under pressu s excess of 1000 s. per scuare inch. Th6 preferred base metal this class of service will usually be plain carbon steel or carbon-molybdenum steel or low cluome-molybdcnum carbon steel; the coating metal for this class of service will usually be chrome steel, chrome nickel steel, monel metal, etc.

The novel method may be employed for manulecturing coated articles that are substantially finished form alter the coating operan or may be employed for manufacturing intermediate articles or workpieces such as ingots, billets, cylinders and the like lrom which final articles are produced by working operations such as forging, rolling etc. The articles may he produced in the form or fiatmemhers such as slabs, plates, etc., or shaped members such as angles, channels and similar shaped forms, or they may be produced as solid cylinders such as 50 bars or as hollow cylinders such as tubes.

To form a flat surfaced article as, for instance,

a thick coated slab from which plate M, such as shown in Fig. 5, is rolled, the coating metal, as for instance l2-H chrome steel, in the form of 55' voltage and feed electrode l at rates controlled to maintain a discharge of predetermined voltage and amperage. Welding head I is provided with electrode feed wheels l6 and includes cables ll and [8 for passing current to plate ll and contact device l9 respectively. Contact device I9 may be of any preferred construction but is preferably shaped along the lines indicated to direct electrode l5 towards the exposed side of plate I l. Welding head H may include a current generator, or generators, or it may be provided with leads to an outside source of current.

Welding head I4 is mounted for vertical as well as longitudinal movement so that electrode i5 may be moved back and forth in a substantially horizontal path across the exposed side of plate II and this path raised either continuously or from time to time to maintain it at or slightly above the level of the fused base metal 20. While only one welding head i4 and one electrode l5 have been shown a plurality of these may be employed. If a plurality of electrodes is used their paths may overlap. Whether one or more electrodes will be used will depend on the length of exposed side of plate H, the purpose being to employ a sumcient number of electrodes 85. to assure that the rising molten metal will always come in contact with fused portions of plate H so that an intermingling of the molten metal 29 and the metal molten from plate H is guarane teed and a proper weld therebetween is assured.

Electrode I5 may be of any shape or character, thus, it may be hollow or solid, round, square etc. Due to its superior penetration an electrode in wire form is at present preferred. Electrode l5 may be of the same or substantially the same composition as the metal of plate I I or it may be of the same or substantially the same composition as molten metal 20. In view of the small amount of metal deposited from electrode IE it may not m necessary to compensate for the loss of constituents thereof in the electric discharge, however, it is contemplated that such compensation may be made when necessary. While. in general, electrode l5 will be of the composition as stated, it need not always be so as it may be made of substantially non-consumable materials such as carbon or tungsten. The use of this type of electrode will be governed by the efi'ects of the carbon or tungsten contaminations on the molten metal.

After welding head or heads ll are moved into position electrode i5 is fed until it almost touches plate H. An arc starter, such as a ball of steel wool, a nail or the like, is interposed between .the end of the electrode and the surface of plate H. A deep blanket of flux I3 is then placed in the bottom of the mold to cover the whole of it to a depth of several inches or more.

Flux i3 should be such that it will not liberate deleterious gas, either as to quantity or kind, when molten or when in contact with molten metal or under the influence cf the heat generated by an electrical energy discharge. Flux l3,

furthermore, should be such that it will not add substantial quantities of undesirable ingredients to or remove desirable ingredients from the molten metal but will flux out impurities. A wide variety of fluxes may be used satisfactorily. silicates, in general, either simple silicates and mixtures thereof, or complex silicates and mixtures thereof, are satisfactory. Aluminates, titanates and similar compounds are likewise satisfactory and may also be used in mixture with silicates. The flux may also include thinning compounds such as feldspar and the like. The flux need not be composed of reacted materials but may be made up of their dried or calcined unreacted components. Thus, in the case of calcium silicates the flux may be made up of CaO and SiOz, in the case'of manganese silicates, it may be made up of Mp0 and SiOz. At present, silicates of the alkaline earth metals, and manganese, aluminum, and iron are, preferred as fluxes. Flux blanket i3 may be placed in the mold in the solidified condition and in broken up form, also it may be placed in mold l2 in the molten condition. After the flux blanket I3 is laid the electrical circuit is closed. The initial surge of current will destroy the arc starter and provide a path for the passage of current between the end of the electrode and the surface of plate H. The electric current discharge will melt metal of the electrode and metal of the surface of plate l I; the current discharge will also melt some of the flux, when the flux is in the solidified condition or raise its temperature when it is molten. The welding head, or heads M will be moved back and forth so that a substantially continuous horizontal band of metal of plate H will at all times be in the molten condition. A continuous band of molten metal may also be obtained without oscillation of the electrodes by employing a sufficient number of closely spaced, and preferably small, electrodes.

Molten metal 26 is then poured into mold l2.

The molten metal is preferably at a temperature proper for pouring and is not superheated so that it will have a minimum tendency to fuse the solid portions of plate H. In this manner, the penetration into plate ii is controlled and maintained throughout the height of plate II. The pouring of molten metal 20 and the raising of welding of the molten metal 20 in contact with plate ll high enough to assure this result.

Thus the electric discharge may be on at or slightly above the level of molten metal 20 and make take place between electrode l5 and metal lL or between electrode l5 and metal H as well as molten metal 20, or between electrode l5 and molten metal 20. Various arrangements may be employed for maintaining the discharge at the predetermined elevation relative to the level of the molten metal 20. At present, I prefer to employ a non-consumable water cooled electrode ,and discharge current through a gap between it and molten metal 20, the electrode being retracted by automatic means to maintain the voltage of the discharge constant. The rate of retraction of this electrode will be exactly equal to the rate of rise of molten metal ,2!) and by raising head M, as through electrically actuated means, in accordance with the retraction the predetermined elevation will be maintained.

To further assure the maintenance of a uniarouses 3 form pen throughout the height of plate ll passa are provided in the walls of mold ii. sage therethrough of a heat exchang uch as water. These passagei 5 rests old is be cooled e a e the cooling solidi 5 he poll a be poured f mold all?) operation is properly com of molten metal will be presii? at the end of the operation "I?" a m durum of shrinkage say .a the cast metal 2E8. To assure to the top of plate H mold 3 ed, he provided with a shrink or similar a vice (not shown) After tl" molten metal has solidified the re 4 E sultant article which corresponds to a coated slab is removed from mold it either for direct use or for working into the final desired article. The slab thus formed will include as the major portion of its thickness base metal 20 to which. 43 is intimately and thoroughly united throughout coating metal H. The union between the coating metal and the base metal is so thorough and complete that the slab is to all intents and purposes, a unitary structure. 5 The slab thus formed will usually be rolled or otherwise worked into plates, sheets or the like. The working operation will not only produce an article of desired shape and size but will also convert the cast metal into work refined metal. For economical reasons the slab will, in general be made many times thicker, as for instance, from to times or more, than the finally desired article so that there will in the workingbe a substantial reduction in thickness C0 and a proportionate reduction in the cost of the operation when figured on unit 01' area of the final article.

As shown, particularly in Fig. 2, the operation may be so carried on to produce an ingot from which two plates l0 maybe rolled. In this case, a pair of plates i I is assembled as by'welding and a space 24 provided between them for the circulation of water or other heat exchange medium. Welding heads H and electrodes l5 are 70 provided on each of the exposed sides of assembled plates ll so that metal of both of the exposed surfaces may be simultaneously melted to commingle with the rising molten metal 20. As disclosed in connection with Fig. 1, the molten 5 metal may be bottom poured or top poured. I1

troi o a l exit in his means t bottom pouring is employed the heat exchange medium is not circulated through the sides and bottom of the passageways in mold i2. If top pouring is employed a heat exchange medium may be circulated through all of the passageways it to accelerate the cooling and solidification or the cast metal. In c case heat exchange me is circulat '1 space M between the completed the The ingot may ated after rated mm fed direc or the on. and of unitary composite products warts may he u.

of one compoy metal of anare of the same char as those gs. l. 2. However, molds .r be of cross section to correspond with t or the composite body to be produced, tum, no cross-section of these molds may be rectangular, circular or polygonal; In the apparatus of 3 and 4 welding heads 54 and molds 52 are arranged relative to each other that electrode t move through a helix like path so can completely cover the exposed surface as e coating metal. When core 25 (Fig. 3) is cylindrical the electrode path will be a helix, when annulus 26 (Fig. l) is circular the electrode paths will also he a helix. As in the case of the arrangements of. Figs. 1 and 2 a sufiiciently large number or small electrodes may be employed to give a substantially continuous band of fused metal and the electrodes merely raisedto maintain the predetermined elevation relative to the molten metal 26.

The arrangement of Fig. 3 is specifically in tended to produce a composite body having a core 25 to which is united an envelope of cast metal 20. Such a body will generally serve as a workpiece from which the internally coated seamless tube 21 of Fig. '7 may be manufactured' In the usual case the composite body is opened through its center as by passing through a Mannesmann mill, or by trepanning, etc., to form a thick walled tube and the final seamless tube made by rolling the thick walled tube to the desired dimensions. Tube 21 may also be drawn or cold rolled as desired.

The arrangement of Fig. 4 is specifically intended to produce a composite body having an envelope 26 to which is united a core of cast metal 20. Such a body will generally serve as a'workpiece from which externally coated seamless tube 28 of Fig. 6 may be manufactured.

Generally the composite body is first opened 1 through its center as by passing it through a Mannesmann mill, or by trepanning, etc., to form a thick walled tube which is rolled into the final tube 28,01 desired dimensions. Tube 28 may also be drawn or cold rolled if desired. When carrying out the novel method with the arrangements of Figs. 3 and 4 the cast metal" may be top poured or bottom poured. With top pouring penetration can be better controlled and shrinkage defects minimized by circulating acoolmedium may be circulated to facilitate the control of penetration.

workpieces from which internally and externally coated seamless tube 29 of Fig. 8 are manu factured maybe made by combining the procedure illustrated in Figs. 3 and 4. In making such workpieces a core is centered in the mold as in Fig. 3 and an annulus placed against the mold sides as in Fig. 4; the cast-metal is poured in the space between the annulus and core. To unite the cast metal to the core an electrode or electrodes are rotated around the core beneath a blanket of flux and the current discharged to fuse a depth of the core soas to obtain a union between the cast metal and the core metal. An electrode or electrodes are also rotated proximate the inner wall of the annulus beneath a blanket of flux and the current discharged to fuse'a depth of the annulus so as to obtain a union between the cast metal and the metal of the annulus. Again a plurality of small closely spaced electrodes may be employed. The seamless tube 29 is made by working as explained in connection with tubes 21 and 28. Tube 29 may have an inner coating 30 of one composition and tion is not limited to this for the coating metal.

may be cast and the base metal placed in the molds in the solidified condition. Generally, the metal or higher melting point will be placed in the mold in the solidified condition and the metal of lower melting point cast in the mold. By 1'01- lowing this rule troubles due to excessive fusion of the solid metal will be avoided and penetration into the solid metal more accurately controlled.

I claim:

1. The method of uniting metals which comprises, providing a mold space defined at least in part by a non-horizontal surface of a'solid metal body, pouring molten metal into said mold space beneath a blanket of protective flux therein to progressively cover said non-horizontal surface, the molten metal being supplied from a molten metal source externalto said mold space, and uniting the metals by fusing a depth of the solid metal defining said non-horizontal surface as solid metal.

the'molten metal is poured to intermingle the metals, the fusion of the solid metal being effected by the discharge of electric current through a gap beneath the surface of the blanket of flux. 2. The method of manufacturing metal articles which comprises, providing a mold space defined at least in part by a non-horizontal surface of a solid metal body, pouring molten metal into said mold space beneath a blanket of protective flux therein to progressively cover said non-horizontal surface, the molten metal being supplied from a molten metal source external to said mold space,

and uniting the metals by fusing a depth of the solid metal defining said non-horizontal surface at substantially the molten metal level as said molten metal rises to coversaid non-horizontal surface, the fusion of the solid metal being effected by the discharge of electric current through a gap beneath the surface of the flux blanket.

3. The method of manufacturing metal articles which comprises, providing a mold space defined at least in part by'a non-horizontal surface of a solid metal body, pouring molten metal into said mold space beneath a blanket of protective flux therein to progressively cover said non-horizontal surface, the molten metal being supplied from a molten metal source external to said mold space, fusing a depth of the solid metal in the zone of the meeting line of said non horizontal surface and the molten metal surface as the moltenmetal rises in the mold space, the fusion of the solid metal being effected by the discharge of electric current through a gap beneath the surface of a blanket of flux, said gap being positioned sufficiently adjacent the solid metal to fuse the solid metal directly by the heat generated at the gap.

4. The method of manufacturing metal articles which comprises, providing a mold space defined at least in-part by a non-horizontal surface of a solid metal body, pouring molten metal into said mold space beneath a blanket of protective flux therein to progressively cover said non-horizontal surface, the molten metal being supplied from a molten metal source externalto said mold space, discharging electric current beneath the surface of the blanket of flux through a gap between the end of a fusible metal electrode and the metal in the zone of the meeting line of said non-horizontal surface and the molten metal surface to fuse a depth of the solid metal defining said nonhorizontal surface directly by the heat of the dis; charge, whereby the metals are intermingled, and controlling the dissipation of heat from the metals to fuse a substantially constant depth of the ROBERT x. HOPKINS. 

